Dionysus is a Greek God. He is the God of WIne, Parties, Madness, and Ecstasy. He is the son of Zeus and the mortal woman Semele. In Ancient Greece, he was a demigod hero who invented wine. Eventually, his father raised him to Olympus to become a god. Due to Hera's rage over his ascension, Hestia gave up her seat on the Olympian Council to him as a show of support.
Currently, he lives at Camp Half-Blood in Long Island because his father is punishing him for beginning a relationship with a wood nymph that Zeus had his eye on. He has seven years left of his sentence there.